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Imac Randomly Freezes and Restart
Posted by: graylocks
Date: April 12, 2021 01:57PM
For the past few month my iMac has been randomly freezing. Left to its own devices it will restart. If i'm using it when it happens I'll restart it. I have absolutely no idea why this is happening or where to start to isolate the problem.

I had thought it started when I began the new Brave browser a while back and I thought maybe with Chrome and Safari open I was asking too much. Last week I stopped using Brave and even rarely left Safari open. Just earlier today I was thinking the Mac hadn't frozen in almost a week and then BAM, it just happened again. Chrome was in use with maybe a dozen open tabs. Mail, preview, Messages, Moneydance, and Calculator were also open.

How do I go tracking down the culprit? This occurs a couple a times a week, generally.

2019 iMac. 3GHZ, 6 Core I5 8GB RAM running Big Sur 11.1.



"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama
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Re: Imac Randomly Freezes and Restart
Posted by: btfc
Date: April 12, 2021 02:15PM
Start with the basics:

Unplug external devices

Check Logs:

[www.chriswrites.com]

Run Disk Utility

Run Apple Diagnostics:

[support.apple.com]

(8 gigs RAM sounds like Apple memory; otherwise reverting to factory is a good call)

Long shot but I’ve seen it: sticky power button
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Re: Imac Randomly Freezes and Restart
Posted by: btfc
Date: April 12, 2021 02:18PM
Also, if you have another system to boot from, try that.

Sometimes a fresh system will solve such issues.
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Re: Imac Randomly Freezes and Restart
Posted by: graylocks
Date: April 12, 2021 02:31PM
Quote
btfc
Start with the basics:

Unplug external devices

Check Logs:

[www.chriswrites.com]

Run Disk Utility

Run Apple Diagnostics:

[support.apple.com]

(8 gigs RAM sounds like Apple memory; otherwise reverting to factory is a good call)

Long shot but I’ve seen it: sticky power button

I have to go mow the lawn but I'll give those a shot when i'm done. thanks.

External devices are:
Back Up Hard drive
Logitech speakers
CD/DVD player
FiFine USB Mic
Logitech 920 Cam
iPhone 6s via Epoccam app



"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama



Edited 1 time(s). Last edit at 04/12/2021 02:31PM by graylocks.
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Re: Imac Randomly Freezes and Restart
Posted by: Bernie
Date: April 12, 2021 03:46PM
Ya got four slots and only 8 Gb of RAM.

OWC only sells 8 Gb sticks and Up for your iMac.

Best in matched pairs.

Ya got a Muscle car with a 2 barrel carb. It goes 0-60 and runs out of gas. But it always restarts.

That is my rant and I am sticking to it.




Staunton, Virginia
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Re: Imac Randomly Freezes and Restart
Posted by: graylocks
Date: April 12, 2021 03:53PM
Quote
Bernie
Ya got four slots and only 8 Gb of RAM.

OWC only sells 8 Gb sticks and Up for your iMac.

Best in matched pairs.

Ya got a Muscle car with a 2 barrel carb. It goes 0-60 and runs out of gas. But it always restarts.

That is my rant and I am sticking to it.

I'm pretty sure this iMac is not user upgradeable. the 27" is but not the 21.5. that's what i recall reading when i bought it.



"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama



Edited 1 time(s). Last edit at 04/12/2021 03:53PM by graylocks.
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Re: Imac Randomly Freezes and Restart
Posted by: btfc
Date: April 12, 2021 04:07PM
“ I'm pretty sure this iMac is not user upgradeable. the 27" is but not the 21.5 “

Correct.
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Re: Imac Randomly Freezes and Restart
Posted by: anonymouse1
Date: April 12, 2021 05:53PM
Try another user account?
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Re: Imac Randomly Freezes and Restart
Posted by: Bernie
Date: April 12, 2021 06:48PM
OWC shows you how to replace the memory in a 21.5 inch iMac 2019

OWC upgrades.

Didn't say it was easy.




Staunton, Virginia
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Re: Imac Randomly Freezes and Restart
Posted by: Sarcany
Date: April 12, 2021 06:56PM
Someone will call it out as apocryphal, but it's been my experience that almost every person using the Brave browser on a Mac has a Mac loaded with malware.

Done a Malwarebytes scan?



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Re: Imac Randomly Freezes and Restart
Posted by: graylocks
Date: April 12, 2021 07:54PM
Quote
Sarcany
Someone will call it out as apocryphal, but it's been my experience that almost every person using the Brave browser on a Mac has a Mac loaded with malware.

Done a Malwarebytes scan?

Malwarebytes says I'm squeaky clean.

Disk Utility says I don't need any First Aid.



"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama
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Re: Imac Randomly Freezes and Restart
Posted by: C(-)ris
Date: April 12, 2021 09:56PM
Try running the hardware test and see if it comes up with anything: [support.apple.com]



C(-)ris
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Re: Imac Randomly Freezes and Restart
Posted by: space-time
Date: April 12, 2021 09:57PM
I never heard of Brave browser until now.
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Re: Imac Randomly Freezes and Restart
Posted by: graylocks
Date: April 12, 2021 09:59PM
Quote
space-time
I never heard of Brave browser until now.

I saw it mentioned favorably on Tidbits a few months ago.



"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama
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Re: Imac Randomly Freezes and Restart
Posted by: graylocks
Date: April 12, 2021 10:07PM
Disconnect all external devices except keyboard, mouse, display, Ethernet connection (if applicable), and connection to AC power.

This is the instruction for Apple diagnostics. Then it says: Turn on your Mac, then immediately press and hold the D key on your keyboard as your Mac starts up.

I'm going to assume they don't really mean disconnect the AC Power...

Edit: oops, missed the word except. maybe i shouldn’t do this so late. ok. going in!



"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama



Edited 1 time(s). Last edit at 04/12/2021 10:13PM by graylocks.
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Re: Imac Randomly Freezes and Restart
Posted by: Sarcany
Date: April 12, 2021 10:34PM
Re: Logs... In Big Sur, the Console will not show you all of the relevant logs.

Look in the /Library/Logs/DiagnosticReports folder for any log files ending in the word "panic."

Got any of those log files?



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Re: Imac Randomly Freezes and Restart
Posted by: graylocks
Date: April 12, 2021 10:47PM
Quote
Sarcany
Re: Logs... In Big Sur, the Console will not show you all of the relevant logs.

Look in the /Library/Logs/DiagnosticReports folder for any log files ending in the word "panic."

Got any of those log files?

just looked. no panic.



"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama
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Re: Imac Randomly Freezes and Restart
Posted by: graylocks
Date: April 12, 2021 11:13PM
Ran Apple Diagnostics.

No Issues.

sigh...



"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama
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Re: Imac Randomly Freezes and Restart
Posted by: Sarcany
Date: April 12, 2021 11:24PM
On the next restart, please run this in the Terminal and let us know the results.

log show --predicate 'eventMessage contains "Previous shutdown cause"' --last 24h

There should be a numeric code for the shutdown (restart) cause. It may reveal something interesting.



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Re: Imac Randomly Freezes and Restart
Posted by: graylocks
Date: April 13, 2021 12:26AM
Quote
Sarcany
On the next restart, please run this in the Terminal and let us know the results.

log show --predicate 'eventMessage contains "Previous shutdown cause"' --last 24h

There should be a numeric code for the shutdown (restart) cause. It may reveal something interesting.

i am very Terminal ignorant and fearful. when it opens up i type that in. then do i hit return or anything?

what is being typed after log show. is it dash dash or space dash dash?



"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama



Edited 1 time(s). Last edit at 04/13/2021 12:27AM by graylocks.
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Re: Imac Randomly Freezes and Restart
Posted by: Sarcany
Date: April 13, 2021 06:57AM
Quote
graylocks
i am very Terminal ignorant and fearful. when it opens up i type that in. then do i hit return or anything?

what is being typed after log show. is it dash dash or space dash dash?

space+hyphen+hyphen...

You can copy/paste it from my post. Tap the <Return> key at the end to run the command. It should take a minute or so to pull the info from the logs and then the output should be in the form of a nicely formatted table.

The log command is not one of those that can hose your Mac with a typo. It just reads logs. In this case, it's also sorting through your logs to find any messages containing "Previous shutdown cause" from the last day and reporting the result.

This is not a weird thing I pulled out of a hat. It's advice that you'll find recommended frequently online when a Mac is rebooting or shutting down unexpectedly.



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Re: Imac Randomly Freezes and Restart
Posted by: raz
Date: April 13, 2021 09:04AM
FWIW, my old MacPro was doing this. It was the power supply.



--------------

Embarassing myself on the Internet since 1978.
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Re: Imac Randomly Freezes and Restart
Posted by: graylocks
Date: April 13, 2021 04:12PM
Quote
Sarcany
On the next restart, please run this in the Terminal and let us know the results.

log show --predicate 'eventMessage contains "Previous shutdown cause"' --last 24h

There should be a numeric code for the shutdown (restart) cause. It may reveal something interesting.

This is what I pulled. Mean anything? I'm also wondering if at this point 24hr doesn't cover yesterday's original freeze. can i enter any amount of hours in the command in Terminal?





"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama
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Re: Imac Randomly Freezes and Restart
Posted by: Sarcany
Date: April 13, 2021 07:15PM
5 is user-initiated.

3 is a hard-shutdown from loss of power or someone holding the power-button.

Yes, you can look for older events, but it takes much longer to run the search through the logs. Don't be surprised it it churns for a few minutes before showing a result.

Try this:
log show --predicate 'eventMessage contains "Previous shutdown cause"' --last 5d



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Re: Imac Randomly Freezes and Restart
Posted by: graylocks
Date: April 13, 2021 09:13PM
Quote
Sarcany
5 is user-initiated.

3 is a hard-shutdown from loss of power or someone holding the power-button.

Yes, you can look for older events, but it takes much longer to run the search through the logs. Don't be surprised it it churns for a few minutes before showing a result.

Try this:
log show --predicate 'eventMessage contains "Previous shutdown cause"' --last 5d

ran it again and the only thing different is that it picked up the freeze earlier on 4/12 that prompted me to post. That earned a 3 and I was nowhere near the power button so there was some loss of power. when it freezes the screen is still on and it usually takes about a minute or so before it restarts. is it marking the loss of power from the freeze or from the point it restarts?



"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama
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Re: Imac Randomly Freezes and Restart
Posted by: Sarcany
Date: April 13, 2021 10:21PM
Quote
graylocks
...That earned a 3 and I was nowhere near the power button so there was some loss of power. when it freezes the screen is still on and it usually takes about a minute or so before it restarts. is it marking the loss of power from the freeze or from the point it restarts?

Unless the power-button is sticky and jammed in (which happens), something seems wonky in hardware.

A report from the Apple Hardware Test that it found no trouble isn't determinative.

Got AppleCare+ ...?

This seems to be a serious enough problem to merit a Genius Bar appointment. Insist that they run a full AST2 diagnostic and not just their MRI (quick) test. They may need to hold onto the iMac for a couple of days before they can run the full test as it takes some time and they've got a backlog these days. Always update your backups before bringing a Mac to Apple as they are notorious for wiping drives.



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Re: Imac Randomly Freezes and Restart
Posted by: graylocks
Date: April 13, 2021 10:48PM
No AppleCare and I've had it more than a year.

Thanks for your help. I've made a note of what you're recommended I tell them but I think i'll just live with this for now. Maybe when things are more back to normal I'll take it in.



"Success isn't about how much money you make. It is about the difference you make in people's lives."--Michelle Obama
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